Carburtor



May 25 1926 J. F. MCCARTHY ET AL I CARBURETOR- Filed May 14, 1919 mwN-fons s s E N u w J. F. MCCARTHY ET AL May 25 1926.

CARBURETOR Filed May 14; 1919 A4 Sheets-Sheen'I 2 INVENTORS WITNESS May 25 1926.

4 SheetS-Sheei'. 3 l

INVENTOHS May 25 1926. 1,586,097

J. F. MCCARTHY ET AL vCARBURETOR Filed may 14, 1919 4 Sheets-Sheet L ,35 2b ZI WITNESS INVENTORS (uw www Y En@ (www A l Q1 Patented May 25, 1926.

UNITED STATES 1,586,097 PATENT oFFIcE.

JOHN F. MOCABTHY, F PITTSBURGH, PENNSYLVANIA, AND FRANK W. OFELDT, OF

DETROIT, MICHIGAN, ASSIGNORS OF ONE-EIGHTH TO JOHN J LYONS, AND THREE- EIGHTHS T0 JOHN H. WEEKS, BOTH 0F PITTSBURGH, PENNSYLVANIA.

CABBURETOR.

Application led May 14, 1919. Serial No. 296,983. i

Figure 1 is an end elevation with certain parts in vertical section of a carburetor of the vertical type embodying our inventlon.

Figure 2 is a sectional elevation of the same.

Figure 3 is a section on the line III-III of Figure 2, but with the throttle valve in a different position.

Figure 4 is avertical section through the carburetor shown in Figure 3, with certain parts broken away.

Figure 5 is a side elevation of the throttle valve shown in the preceding figures.

Figure 6 is a sectional elevation and Figure 7 an end elevation vof a modified form of up-draft carburetor.

Figure 8 is a side elevation of the throttle valve shown in Figure 6.

Figure 9 is a section on the line IX-IX of Figure 8. Y

Figure 10 is a longitudinal section showing. our invention applied to a carburetor of the horizontal type and with a modified form of throttle valve.

Figure 11 is a section on the line XI-XI of Figure 10. l

Figure 12 is an end view of the throttle shown in Figures 10 and 11, and

Figure 13 is a sectional View on the line XUL-XIII of Figure 12. Y

Our invention has relation to carburetors and is designed to provide a novel and efficient' carburetor which shall be self-compensating under varying conditions of speed and load.

Our invention comprises a carburetor having a plurality of mixing tubes each of which consists of an opening shaped to roduce a zone of depression therein and having a fuel supply jet discharging therein, together with a single throttle device by means of which the mixing tubes are successively put into and out of action.

Our invention also comprises Various other novel constructions, arrangements and combinations of parts hereinafter described and pointed out in the appended claims.

Referring first to thatform of our inven-v tion shown in Figures 1 to 5, the numeral 2 designates a cylindrical mixing chamber contained in a cylindrical casing 3 and having the outlet opening 4 leading to the engine, 5 designates a series of air inlet openin entering the chamber 2 and arranged longichamber 2 at the opposite side of the center. l

In the construction shown there are five openings .in each of the two series. Each of the openings or tubes 5 and 6 is provided with a fuel jet nozzle 7 projecting lpreferably to about the center line of said openings. Each series of these nozzles receives' its supply from a longitudinal passage 8 formed in the base of the carburetor. The openings in said base through which the nozzles are placed and removed are closed by suitable means such as the sciew plugs 9. In the construction shown, one of the passages 8 is supplied with fuel by a connection 10 leading to a constant level float chamber 11 of any suitable or wellknown character. The other passage`8 is supplied with fuel through a connection 12 leading to a second constant level fioat chamber 13 arranged at the opposite sideof the casing 3. The two float chambers may be supplied with thel same character of fuel, or the fioat chamber 13 which supplies the second series of passages 5 may contain fuel of a lower proof, such as kerosene or lower grade gasolene.y

The first mixing tube (shown at 6 in Figure 6) is preferably of smaller diameter than the remainingtubes, being arranged for use in idling. It isgpreferab'ly provided with an adjusting device, such as the screw 14, for controlling the voume of mixture discharged into the chamber 2, and with a second adjusting device such as shown at 15 for controlling the volume of air which is admitted. This idling tube is not shown in Figures 1, 2 and 3, but it will be understood that in these iigures this tube is of the construction and arrangement shown in Figure 6.

All of the mixing tubes 5 and 6 are controlled by a Single throttle of the construction shown in detail in Figure 5. This throttle comprises two heads 16, each of which carries 'a stub shaft 17 which is mounted in suitable bearings in the end of the casing 3. rl`he heads` 16 are connected by a partial barrel portion 18 having one straight edge 19 and having its opposite end formed with a series of steps 20 corresponding in number 'to the number of mixing tubes in each series. This throttlel is journaled centrally within the chamber 2 and is designed to be rotated in opening it in the direction indicated by the arrow in Figure 2 in which it is shown in its wide open position with all the vaporizing tubes opened. As it is moved to this position from the closed position, shown in Figure 3, the tubes 6 are first successively opened; and when these have all been uncovered, the openings 5 of the second series are similarly successively uncovered. In a similar manner upon the reverse movement of the throttle, the tubes 5 are -first successively closed after which the tubes 6 are successively covered. The throttle may be actuated by any suitable connection such as the reach rod 21 (see Figure 1) connected to a bell crank lever 22 on one of the shafts 17 through the medium of the adjustable ,telescoping spring connection 23. In orderto prevent too'rapid opening of the throttle the other arm of the bell crank 22 is connected at 24 to a dash pot plunger 25 operating within the dash pot 26.

Y 5. For this purpose we have shown a water jet pipe 27 having an outlet opening 28 leading into the last mixing tube 5, and the entrance to which is controlled by a springseated check valve 29 having its projecting stem provided with a head 30 which is adapted to be engaged by an anti-friction roller 31 on the bell crank 22 as the throttle is moved to its wide open position where the bell crank engages with the full open stop 32.

Where the carburetor is designed to be used with kerosene or other low test fuel on the second stage, means ma be provided for heating the chamber 2. For this purpose we have shown a lU-shaped heating tube 33 arranged Within said chamber 2, one end having a connection 34 designed to lead to the exhaust gas manifold; and its other end having a connection 35 designed to lead to the muiler. This heating device 33 not only acts to heat the mixture in the chamber 2 but it may be proportioned to act as a filler for said chamber and thus reduce the free cross sectional area of said chamber to about the size of the outlet opening 4, thereby preventing poclreting of the mixture in the chamber.

The form of our invention shown in Fig- -ures 6, 7 8 and 9 is substantially the same as that tirst described, except that instead of having two longitudinal fuel supply passages 8, we provide a single centrally located fuel supply passage 8a from which both sets of fuel supply nozzles 7a lead. This passage 8fl terminates at one end in a cross pipe 36 having oppositely extending arms to either or both extremities of which a constant level float chamber may be connected. This construction provides for placing the float chamber at that side of the carburetor which may be most convenient for any particular setting. The throttle valve shown in these figures is substantially the same as that first described, except that the heads 16"L are completely circular.

In Figures 10, 11, 12 and 13 we have illustrated an embodiment of our invention as applied to a carburetor of thc horizonta type. In this construction'the outlet connection 4b to the engine forms an end extension of the mixing chamber 2b. The mixing tubes and jets 5b, 6" and 7b are arranged in the manner shown in Figures 6 and 7, both series of jets being supplied from the single longitudinal fuel passage 8", and which in turn receives its supply by a connection with the constant level ioat chamber 11b.

The throttle valve shown in these figures is of the same general character as in the previously described constructions, but instead of having a bearing at each end, as in such constructions, it is formed with an internal hub 37 `which is journaled on an overhung bossy 38 projecting inwardly fro one end of the casing 3b. The hub is fastened at 39 to a central actuating shaft or spindle 40. In this construction, the hub 37 may be made to act as a 'filler for properiy proportioning the area of the mixin,D chamber.

By reference to Figure 11, it will be noted that the distance between the two sets of openings 5b and- 6b is approximately equal to the distance between the advance and rear edges of the side portions of the throttle valve, so that the second series of said openings will commence to be uncovered immediately on the uncovering of the openings of the first series.

In these figures, as well as in Figure 7, we have shown the throttle shaft provided with a pointer 41 which is arranged to travel over a series of numerals 42 arranged on one end of the carburetor casing and arranged to correspond with the several Venturi openings. This feature may be applied to all forms of our invention.

It will be noted b reference to Figure 2 that the throttle valve is so arranged that when in its Wide open position its straight edge 19 is substantially flush with the adjacent wall of the opening 4 so that the throttle does not in any way obstruct this openmg.

In effect our improved carburetor comprises a lurality of separate earburetors, each having its own fuel jet'and its own air inlet opening, these separate carburetors being brought successively into and out of operation by the single throttle. The fuel jet nozzles preferably terminate slightly above the level-of the fuel in the float chamber or chambers by which they are supplied, so that the fuel must be drawn out of saidnozzles by the action of the entering air. In this manner the action 'of the mixing tubes which are in action at any particular time is depast the jets is maintained, as figured from the highest and lowest pressures available in the intake cycle of the engine.

The second stage occurs when sufficient tubes, having been made operative, the pressure difference between inlet and outlet orifices of said tubes becomes less than the critical pressure, and the liow of gas mixture is then governed by both the initial and final pressures. This causes a variation of mixtures with varying engine speeds at any setposition of the throttle device, tending to make the mixture leaner with decreasingengine speeds, and richer with increasing engine speeds. This action is very desirable 1n carburetors.

The collective cross-sectional area of the tubes of the first series, and the size of the jets leading thereto is such with respect to the volumetric content of the engine with which the carburetor is to be used, that at all conditions of speed and load under which the engine can possibly operate while these u tubes arethe onlyT ones uncovered by the throttle, that the absolute pressure difference on opposite sides of the tubes, as figured from the law of flow of gases through tubes and orifices," is always greater than the critical pressure. By reason ofthisconstruction,

with any number of tubes of the first series uncovered, it will be impossible to supply a sufcient amount of air and fuel to decrease the pressure on opposite sides of the tubes below the critical pressure. This insures that any variation in the engine speed,

vcaused by varying the load, with any number of tubes of the first series open, will not afiect'the flow of the mixture.

However, when the throttle is moved so as to uncover one or more of the tubes 5, the admission of air therethrough into the chamber 2 causes a reduction of the depression in such chamber and the absolute pressure difference may then not be greater than the critical pressure. Hence, after one or more of the tubes 5 are opened, the carburetor acts like other carburetors having fixed orificeswhen the speed `and load changes butv the throttle remains fixed.

1. In a carburetor, a throttle chamber having an outlet leading to the intake of the engine, and also having a plurality of separate air inlets opening into said chamber, a separate' fuel nozzle dischargino into each of said inlets, and a throttle in said chamber arranged to successively uncover different of said inlets without changing the area' of said outlet, certain of said inlets being so proportioned that with predetermined engine capacities with which the carburetor is adaptedto be used the pressure difference across said inlets will not drop below the critical point, Vsubstantially as described.l

2. In a carburetor, a throttle chamber having an outlet leading to the intake of the engine, a plurality of separate air inlets opening into said chamber, said inlets being arranged in=two series, a separate fuel noz- 'zle discharging into each of said inlets, and

a throttle in said chamber arranged to successively uncover and cover different of said inlets Without changing. the area of said outlet, one of said series of air-inlets being so proportioned that with predetermined engine capacities with which the carburetor is ada ted to be used the pressure difierence t ereacross will .not drop below the critical point, substantially as described.

In testimony whereof, we have hereunto set our hands.

JOHN F. MCCARTHY. FRANK W. lOFELDT. 

